Abstract

Positronium annihilation lifetime spectroscopy (PALS) has been used to depth profile the densification induced in a porous low-dielectric constant (k) thin film by typical device integration processing, including exposure to plasmas and oxygen ashing. Such “integration damage” has previously been observed as an undesirable increase in k accompanied by shrinkage in the porous film thickness. PALS confirms that the structural damage is confined to a surface layer of collapsed pores with the underlying pores being undamaged. The dense layer thickness determined by PALS increases with plasma exposure time.